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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#ifndef CINE_UNPACK_H
#define CINE_UNPACK_H
#include "common/scummsys.h"
namespace Cine {
/**
* A LZ77 style decompressor for Delphine's data files
* used in at least Future Wars and Operation Stealth.
* @note Works backwards in the source and destination buffers.
* @note Can work with source and destination in the same buffer if there's space.
*/
class CineUnpacker {
public:
/** Returns true if unpacking was successful, otherwise false. */
bool unpack(byte *dst, const byte *src, int srcLen);
private:
/** Reads a single big endian 32-bit integer from the source and goes backwards 4 bytes. */
uint32 readSource();
/**
* Shifts the current internal 32-bit chunk to the right by one.
* Puts input carry into internal chunk's topmost (i.e. leftmost) bit.
* Returns the least significant bit that was shifted out.
*/
int rcr(int inputCarry);
int nextBit();
uint16 getBits(byte numBits);
/**
* Copy raw bytes from the input stream and write them to the destination stream.
* This is used when no adequately long match is found in the sliding window.
* @param numBytes Amount of bytes to copy from the input stream
*/
void unpackRawBytes(uint16 numBytes);
/**
* Copy bytes from the sliding window in the destination buffer.
* This is used when a match of two bytes or longer is found.
* @param offset Offset in the sliding window
* @param numBytes Amount of bytes to copy
*/
void copyRelocatedBytes(uint16 offset, uint16 numBytes);
private:
int _datasize; //!< Bytes left to write into the unpacked data stream
uint32 _crc; //!< Error-detecting code
uint32 _chunk32b; //!< The current internal 32-bit chunk
byte *_dst; //!< Destination buffer pointer
const byte *_src; //!< Source buffer pointer
};
} // End of namespace Cine
#endif
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